The present invention relates to a guide assembly, and in particular a guide assembly for locating the mechanical axis of a bone.
During surgery it is often necessary to locate the mechanical axis of a bone. For example, during knee surgery it is necessary to find the mechanical axis of the femur so that the femur can be appropriately resected in order to properly fit a femoral prosthesis. It is known to determine the angle between the anatomical and mechanical axes using pre-operative x-ray or other images. During the procedure, the anatomical axis can be determined using an intramedullary rod, which is located in the bone's intramedullary canal. The mechanical axis can then be determined with reference to the pre-operative image data and the intramedullary rod. A disadvantage of this technique is the requirement to locate an instrument in the intramedullary canal.